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Commit 1c3c5eab authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
Browse files

sched/core: Enable might_sleep() and smp_processor_id() checks early 



might_sleep() and smp_processor_id() checks are enabled after the boot
process is done. That hides bugs in the SMP bringup and driver
initialization code.

Enable it right when the scheduler starts working, i.e. when init task and
kthreadd have been created and right before the idle task enables
preemption.

Tested-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170516184736.272225698@linutronix.de


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 69a78ff2

init/main.c

+10 −0
Original line number Diff line number Diff line
@@ -414,6 +414,16 @@ static noinline void __ref rest_init(void) 
	rcu_read_lock();

	kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);

	rcu_read_unlock();



	/*

	 * Enable might_sleep() and smp_processor_id() checks.

	 * They cannot be enabled earlier because with CONFIG_PRREMPT=y

	 * kernel_thread() would trigger might_sleep() splats. With

	 * CONFIG_PREEMPT_VOLUNTARY=y the init task might have scheduled

	 * already, but it's stuck on the kthreadd_done completion.

	 */

	system_state = SYSTEM_SCHEDULING;



	complete(&kthreadd_done);



	/*

kernel/sched/core.c

+3 −1
Original line number Diff line number Diff line
@@ -6238,8 +6238,10 @@ void ___might_sleep(const char *file, int line, int preempt_offset) 


	if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&

	     !is_idle_task(current)) ||

	    system_state != SYSTEM_RUNNING || oops_in_progress)

	    system_state == SYSTEM_BOOTING || system_state > SYSTEM_RUNNING ||

	    oops_in_progress)

		return;



	if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)

		return;

	prev_jiffy = jiffies;

lib/smp_processor_id.c

+1 −1
Original line number Diff line number Diff line
@@ -28,7 +28,7 @@ notrace static unsigned int check_preemption_disabled(const char *what1, 
	/*

	 * It is valid to assume CPU-locality during early bootup:

	 */

	if (system_state != SYSTEM_RUNNING)

	if (system_state < SYSTEM_SCHEDULING)

		goto out;



	/*